Analysis Of The Kinematics And Lower Limbs Injury Of Pedestrian In Pedestrian-vehicle Collisions Based Onaccident Video Records

As vulnerable road users,pedestrian are extremely vulnerable in pedestrian-vehicle collision accidents.With the development of vehicle safety technologies and traffic management,the road traffic fatalities in developed countries have fallen,however,the proportion of pedestrian fatalities is increasing.In 2007 to 2013 years,the number of road traffic fatalities has been decreased by 23.3% in United States,by 32.5% in Germany,by 34.1% in Japan.However,probability of pedestrian fatalities has increased by 3% in United States,by 3% in Germany,by 4% in Japan.Therefore,the effectiveness of automobile safety technology is unbalanced for pedestrian.In China,although the proportion of pedestrian fatalities did not change,but there are still 15,000 pedestrians died in traffic accident each years.Therefore,the issues of pedestrian safety need to be more concerned.The puepose of this study was to investigate the characteristics of pedestrian accidents based on videos.With the advantage of video information,the paper analyzed of the emergency posture of pedestrians before collision,the kinematic response of pedestrians during the collision process and the landing mechanism of pedestrian.On this basis,the injury mechanism of pedestrian was deeply understood,and the injury mechanism of lower limbs under running posture was analyzed by numerical model.200 cases were collected from internet in this paper,and the database for the pedestrian accidents video information was establishted based on the codebook of CIDAS.The kinematics and scene was counted and analyzed.The result shown that 24.2% of pedestrian were running,17.7% of pedestrian stoping and to avoid,and 10.5% of pedestrian were walking.In addition,we found that the vehicles may be an important factor to effect the vision of drivers,and 45% of the driver's vision is affected by other vehicles on the road.According to the videos,pedestrians are more prone to rotation,especially collision with the lower-front vehicle or highspeed crash.In this paper,the pedestrian landing mechanism was classified according to the kinematic and landing posture of pedestrians,and the probability of that the pedestrian was thrown up and level landing is the highest.Multi-rigid body model is an important tool to study pedestrian injury.The pedestrian is usually thrown up and rotated after collision with vehicle.Therefore,a multi-body model was used to analyze the correlation between the pedestrian's rotation angle and the head secondary injury impact to the ground.Pedestrian rotation angles has a linear correlation with the impact speed.The lower front structures caused large pedestrian rotation motion.The head injuries caused by the ground was serious than caused by impact to the vehicle in the lower impact velocity.In the higher impact vehocity,the head injuries due to impact to the vehicle more serious.The pedestrian head injury caused by collision with the ground has important relationship with pedestrian rotation angle and has big influence with pedestrian rotation angle velocity.In the collision moment,the pedestrian postures of running or emergency stop ready to avoid were observed and appears high frequency.For the previous studies,the researchers pay more attention to study the injury mechanism of lower limbs under pedestrian normal gait,and did not pay attention to study the effect of pedestrian's emergency posture on lower limb injuries.Therefore,this study analyzed the effects of different postures on lower limb injury based on THUMS V4.02 Finite Element model,and it is found that running posture more likely to cause the knee ligament tearing due to the knee bending angle.At the same time,the influence of the vehicle front structure parameters on the pedestrian lower limb injury was studied.The influence of the height of the bumper on the injury of the pedestrian lower limbs was greater.